Submitted to: Vadose Zone Journal
Publication Type: Peer reviewed journal
Publication Acceptance Date: 5/8/2007
Publication Date: 8/1/2008
Publication URL: http://www.ars.usda.gov/SP2UserFiles/Place/53102000/pdf_pubs/P2200.pdf
Citation: Segal, E., Bradford, S.A., Shouse, P.J., Lazarovitch, N., Corwin, D.L. 2008. Integration of Hard and Soft Data to Characterize Field-Scale Hydraulic Properties for Flow and Transport Studies. Vadose Zone Journal. 7(3):878-889. Interpretive Summary: Accurate characterization of water flow behavior in the field is critical to understand, quantify, and manage agricultural production and the transport and fate of a variety of contaminants in the environment. Computer models that are used to simulate water flow are frequently hindered by our inability to accurately quantify the variability of soil properties that control water flow (hydraulic properties) in the field. In this work, water flow in the field is characterized using a wide variety of measured and estimated soil hydraulic properties and computer modeling tools. This manuscript provides a real-world example of how to combine information and approaches, to tackle the difficult challenge of characterizing the hydraulic properties at a field site.
Technical Abstract: Field-scale flow and transport studies are frequently conducted to assess and quantify a variety of environmental and agricultural scenarios. The utility of field-scale flow and transport studies, however, is frequently limited by our inability to characterize the heterogeneous distribution of hydraulic properties at these sites. We utilized both “hard” and “soft” data sets of field and laboratory scales in conjunction with pedotransfer functions, interpolation algorithm, and numerical modeling to characterize the hydraulic properties of the vadose zone at two 5x5 m field plots. Hard data was used to quantify the magnitude of the hydraulic properties, relationships between water pressure, water content, and hydraulic conductivity, at selected locations in these plots. It included laboratory and field measurements of the hydraulic properties from undisturbed cores and the instantaneous profile method, respectively. More abundant soft data included inductive electromagnetic readings and approximate particle size distribution information. Interpolation algorithms were used to simulate the heterogeneity on these plots. Numerical modeling of steady-state water infiltration and redistribution experiments was used to compare between laboratory-scale and field-scale hydraulic properties and to refine our conceptual model of the vertical and lateral flow at this site. Good agreement between simulated and measured water contents and water pressure heads was obtained, indicating that field-scale hydraulic properties have been accurately quantified for these conditions. The novelty of this work consists of integrating all of the hard and soft data to characterize the field site. This manuscript provides a real-world example of how to combine information and approaches, to tackle the difficult challenge of characterizing the hydraulic properties at a field site.